Gtk3: Fix various menu colors

chrome/browser/ui/libgtkui/native_theme_gtk3.h

Index: chrome/browser/ui/libgtkui/native_theme_gtk3.h
diff --git a/chrome/browser/ui/libgtkui/native_theme_gtk3.h b/chrome/browser/ui/libgtkui/native_theme_gtk3.h
index 1826e778a5386b2a57617612de156ba3ff176ac9..72920a54f8bc7ada726632d9379306d268d741ef 100644
--- a/chrome/browser/ui/libgtkui/native_theme_gtk3.h
+++ b/chrome/browser/ui/libgtkui/native_theme_gtk3.h
@@ -33,6 +33,8 @@ class NativeThemeGtk3 : public ui::NativeThemeBase {
   NativeThemeGtk3();
   ~NativeThemeGtk3() override;
 
+  SkColor LookupGtkThemeColor(ColorId color_id) const;
+
   // Returns various widgets for theming use.
   // TODO(thomasanderson): Remove all of these.
   GtkWidget* GetWindow() const;